Russia's air force has struck the area around the Islamic State-held ancient city of Palmyra, the defence ministry said Monday, as Moscow pressed on with its bombing campaign in Syria.

"Su-25 jets hit a fortified IS position in the Tadmur area of Homs province," Moscow's defence ministry said in a statement, using the Arabic name for Palmyra.

"As a result of a direct strike, a fortification, an underground bunker and anti-aircraft artillery were destroyed."

It appeared to be the first time that Russia has confirmed a strike close to the UNESCO World Heritage site, after Moscow denied Syrian state television claims that it hit the ancient city in early October.

Rami Abdel Rahman, head of the Brtiain-based Syrian Observatory for Human Rights, also said that Russian planes had targeted Palmyra with strikes on Monday.

Khaled al-Homsi, an activist from Palmyra, said that Russian air strikes on Monday struck the ancient citadel on the western edges of the historical site.

"The extent of the damage could not be verified," he told AFP.

Russia did not specify when the strikes took place but said its jets struck over 237 targets in Syria over the past two days in a statement Monday.

Russian warplanes pounded sites belonging to the Islamic State and Al-Qaeda affiliate Al-Nusra Front "terrorist groups" in the Homs, Hama, Latakia, Damascus, Aleppo and Raqa provinces, Moscow said in a statement.

In Aleppo province, Moscow said it hit a training camp for foreign fighters and an improvised explosive device production plant, and said in the Hama province it destroyed two armoured vehicles.

Russia's military said it also took out a key Al-Nusra Front command post on a strategic hill in the coastal Latakia region.

The latest strikes came after the broadest international talks to end the conflict were held on Friday in Vienna.

For the first time, the meeting brought together all the main outside players in the crisis, including Russia and Iran, key allies of the government of President Bashar al-Assad.

Participants agreed to ask the United Nations to broker a peace deal between the regime and opposition – which were not represented at the talks – to clear the way for a new constitution and UN-supervised elections.

Russia has been bombing in Syria since the end of September to help troops loyal to Assad fight what it calls "terrorists".

The US and its allies in a separate coalition bombing IS say that Moscow is mainly targeting more moderate groups fighting Assad.